1. Technical Field
The present invention relates in general to the field of computers, and in particular to protecting a computer from physical shock. Still more particularly, the present invention relates to a method and system for temporarily disabling a hard drive's physical shock protection feature.
2. Description of the Related Art
Most of the components of a computer, including a notebook Personal Computer (PC), are able to take physical shock, resulting from an event such as being dropped, without permanent damage. This is due to the semi-rigid design of the packaging (case) of the computer, and the fact that most of the critical components inside the computer are Integrated Circuit (IC) chips that have no moving parts. However, disk drives, and particularly Hard Disk Drives (HDDs) are prone to permanent damage from physical shock (impact).
To protect the HDD in a notebook PC, many HDDs are shock-mounted on rubber or gel-filled washers and corner pads. As noted above, the semi-rigid case of the notebook PC is designed to absorb energy (flex), thus providing additional impact protection. While such protection may be adequate if the read/write head on the HDD is parked and not operating above the media disk inside the HDD, the HDD is nonetheless likely to be permanently damaged if a read/write operation is occurring when the notebook PC is dropped.
To provide protection to an HDD that is dropped during a read/write operation (in which the drive head is flying over the media disk), International Business Machines (IBM®) of Armonk, N.Y., has developed a feature called Hard Drive Active Protection System (APS). APS utilizes sensors (accelerometers) that detect a dramatic change in the computer's orientation (such as being dropped, kicked, flipped, etc.). The APS uses a signal from the sensors to predict a physical shock that could potentially be transmitted through the notebook PC to the HDD and cause damage to the HDD. As the cliche goes, it's not the fall that hurts, it's the sudden stop. Thus, APS detects that the notebook PC is falling (or otherwise moving in an unhealthy manner), and predicts an imminent physical shock that is likely to permanently damage the HDD that is in a read/write mode of operation. To avoid such damage, APS suspends HDD operations by parking the read/write head of the HDD and stopping the hard drive platters from spinning (assuming that a read/write operation was occurring during the fall). The parking/stopping step takes well less than 500 milliseconds, which is typically less than the time it would take the notebook PC to fall from a user's lap to the ground. Furthermore, the APS can park/stop the HDD in response to rough jiggling, such as may occur while being held by a pedestrian user, while in a vibrating industrial environment, etc. In addition, APS can be configured to ignore small sources of vibration, such as repetitive vibrations experienced on a commuter train, that are not likely to be indicative of imminent physical shock.
Setting up APS on the notebook PC begins by setting APS to the “Enabled” mode. Once in this mode, APS behavior can be adjusted, using either a motion sensitivity slider bar on a Graphical User Interface (GUI), or by checking condition boxes. That is, a slider bar can be moved with a pointer to make the APS more or less sensitive to movement, resulting in the HDD being parked and stopped according to this sensitivity level. Alternatively, activity boxes describing general conditions for activating APS can be checked. Such conditions may include ignoring small, repetitive vibrations such as those experienced when riding on a train.
After the APS detects movement (fall, vibration, etc.) of the notebook computer that is indicative of potential shock, the HDD is stopped. When the HDD is stopped, the read/write head remains parked and software operations requiring access to the HDD cannot proceed. If the movement of the notebook computer continues to meet certain thresholds, APS will to keep the HDD read/write head parked until the computer remains stable for a predetermined amount of time. From the point in which the notebook computer is again stable, the HDD resumes in approximately 1–3 seconds depending on the situation.
While APS provides excellent protection to the HDD, human factor engineers may be concerned that users will turn off the APS feature if it is annoyingly intrusive. Accelerometer sensitivity and detection algorithms for APS are designed to protect the HDD against worst case scenarios in which the fall or vibration of the notebook computer occurs very quickly. However, APS may periodically stop the HDD in instances in which motion meets certain thresholds, but physical shock is not imminent such as when a user is walking and carrying the notebook computer with the display open (e.g. to see location of the next meeting) or when rough turbulence on airplane occurs. In these instances, HDD stoppage may become annoying as the user cannot continue with any operation that may require HDD access (e.g. opening the calendar to view meeting details). If the annoyance of periodic or unwanted HDD stoppage is too great, then there is a strong potential that the user will decide to permanently turn the APS feature off, thus losing a valuable safety feature of the computer.
What is needed, therefore, is a method and system that will allow a user to utilize APS with minimal annoyances resulting from the HDD being stopped. This may include providing a manual method for temporarily overriding APS activity or a more advanced automatic method that fine tunes APS behavior according to the habits and practices of the user. Preferably, such a method and system will cause the APS to automatically handle physically shock events in a manner prescribed by the user.